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a prop question:


venom 66
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I remember when I was stationed at Pope (69-73) the crew started all 4 engines for their mission, and the FE did not notice the c/bs pulled on the oil shut off valves... you know the rest of the story..

I can state from personal experience, that a T56 engine with zero psi power section oil pressure will run less than 60 seconds before it seizes. I learned this the hard way after being on duty 20 hours and not ensuring the drive spline was in place prior to installing the replacement pump on the agb pad.

Shame on the cr ch and fe for not cw the -6 and -1 pr flt ck list item which says check all cbs for proper setting. Further, what were the AC, CP and FE doing as #3 engine comes on speed and the power section oil pressure is still zero.

It's been a very long time since I started a T56 engine but as I recall after I saw enrichment cutback the next thing to look for was positive indication of oil pressure. There were specific limits but don't remember them.

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The aircraft was on the ground. There were 5 other Herks + the Helos there that night all with engines running blowing sand, minum visability and the burning bus. I as a Talon pilot knowing this crew think they were initially momentary, stunned, surprised by the explosion and confused by what was happening to them. There was most likely a few seconds delay before deciding to shut down/feathering the engines. Also, it takes a few rotations before they actually feather. If I recall from the photos in the book "The Guts to Try" the props appear to be feathered. Just my 2 cents.

Hey skip, thanks for the reply. I just read about you in a book called "the commando's" by douglas waller. I was stationed there at King Fahd with the 374th TAW while you were there.

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At the end of the flying day the way I closed the oil tank so valve was to pull the T handle with only DC power on the acft. This precluded unnecessarly exercising the prop feather motors. With the valve closed would then pull the oil tank so valve cbs. I did this for the most part so as to preclude having to service engine oil right away when I really wanted to get on with the post flight/recovery. However, as you say this also prevents oil from leaking into the power section if there is a leaky check valve, a not uncommon occurance. The best part was I could service eng. oil the next morning at my leisure after which would reset the so valve cbs. On more than one instance took grief from flt. line supervision when they saw me servicing oil knowing the bird had landed the previous evening.

That's a great idea, if you don't mind opening up the cowlings to verify the oil shutoff valves opened back up after resetting the c/b. I've ran into a few that like to close, but hate to open again. The Job Guide used to say you had to visually verify that it opened, then someone did a Form 22 to say you could instead listen for it to open. I've run into a couple that would partially open, so I think the new T.O. change is a horrible idea. Also, I've cranked a motor with zero oil pressure, and all the c/b's were pushed in. Thankfully I caught the problem when I was supposed to, during start.

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When I started my FE career or right around that time (85/86) a Safety Sup came out for the flight manual that said you had to visually confirm the valve open if they had been closed after flight for an oil migration.

So I think it was right around the mid 80's that this pretty much went away.

Never could understand why you guys did it anyways, when I was on E3's we would either just motor the engine for 30 sec before crew show or have the crew motor it prior to start and the oil scavenges right back to the tank where it belongs.

Dan

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It seems clarification on my part is in order. First let me say the time frame I'm refering to is early to late sixtys. I think we are all aware how much tech data changes over a period of 45+ years. There was no mention in the TO concerning closing the oil tank sov so as to permit oil service beyond the specified 15 minutes after engine shutdown. It was an informal procedure known to flt. line troops. Additionally, there was no requirement to visably check the valve after closing the cbs. And, in my day to day crew chief duties I didn't do it every time my act. flew. Further, engine oil service was not required after every sortie. On many post flights would have a recovery crew assigned to help. This took care of the 15 minute problem. With regard to what Dan Wilson said about this issue I couldn't agree more. When putting external power on so as the begin the -6 pre flt one of the first things I would look at was oil quanity. If there was one signifiantly lower than the other three would start or motor the engine. Generally would know there was a problem as I approached the acft. as there would be lots of oil on the ramp beneath the affected engine. When my acft. developed a leakdown engine, as soon as time permitted got it fixed. Had enough to worry about without this kind of problem which was easily cured.

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  • 2 weeks later...

"Generally would know there was a problem as I approached the acft. as there would be lots of oil on the ramp beneath the affected engine."

-That would never work on radials or helicopters.

Oh yea, I remember well.

I was a B-47 crew chief and used to ride to work with my neighbor, a KC-97 engine tech. When we would return home in the afternoon I would look pretty much as I did when we went to work. My neighbor, on the other hand, looked as though he had just energed from a barrel of oil. We repeatly tried to explain this his wife but were unsuccessful. Sure was glad I was a jet mech. So was my wife.

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Greaser was the term we used to describe Recip APG and engine Mechanics, in my first few years I worked on recips when there were no 130's or 133's needing work. 124's were the dirtiest followed by 97's

Bob,

If you were to use the term "greaser" in todays air force you would most likely be required to have a friendly chat with the wing political correctness police.:) They would then schedule you for sensativity school. After which you would be required to display a large decal on your car identifiying you as a racist. Oh my God. :rolleyes:

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It wasn't meant as a racial term, at midnight chow you could always pick out recip APG and engine guys. Any recip guy that walked off the flight line after a 12 hour shift with clean fatigues was a goldbricker or spent the shift driveing the line chief around.

Bob,

No intent to criticize, just my attempt at humour.

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We use to pull those breakers at the last flight of the day to shut the oil shut off valves on the E models this would keep the oil from flooding the turbine section.. The breakers was pulled to keep the prop from feathering while pulling the fire handle to shut the oil valve off... We did this if some one still had external, or gtc, power on..

We do the same thing on P-3's if an engine has an oil drain down issue. If "E" handle not pulled, obviously we'd have to motor over the engine prior to start.

Correct.True on E2C and probably P3 as well
You are correct.
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  • 1 month later...

The way i remember prop feathering is mechanically feathered using the conditional lever, which in turn shifts the feather valve on the valve housing causing the fluid to be directed to the outer portion of the dome piston putting it in feather. Electrical by the feather solenoid causing the same basic effect. If everything was working properly, I don't see how they could have re-started the engine in feather due to blade angle on start. The feather valve is 28vdc and same with the other shut-off valves (I'm pretty sure). Not saying it would be impossible.....just unlikely. Remeber...the Herk will make a liar out of you every time.

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Dsnake, I was trying to figure out the cause of your statement.

If I close the oil tank shutoff vavles, my prop does not go to feather. I first pull the "emergency feather" circuit breakers before I pull the "T" handles. That prevents the props from going to feather while the oil tank shutoff valves close. While the oil tankshutoff valves are closed,I pull out the "oil" curcuit breakers. I push the "T" handles back in and - THEN - I push the emergency feather breakers back in.

Nobody will be attempting to start any engines with the props in feather.

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I've think he meant that they where in CUVE position, this position seems that they are in feather but they aren't! CUVE position is used when they are in hostile enviorment when ever APU/GTC will not work anymore (no electricity to give ACvolt)a buddystart is required, and the CUVE position of the blade is the best angle to start.

greetz bob:D

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I've think he meant that they where in CUVE position, this position seems that they are in feather but they aren't! CUVE position is used when they are in hostile enviorment when ever APU/GTC will not work anymore (no electricity to give ACvolt)a buddystart is required, and the CUVE position of the blade is the best angle to start.

greetz bob:D

Seems to me, that back in the day, we called this putting the "prop on the cuff" in case a buddy start was required.

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....a body start!!!.. I think I have an idea of what is a body start but!!!!!!!! I do not want to make a fool out of me!!!. Please just tell me what is a body start!. You do not mean external power like CSU......you mean something else!!..no no no I have to read the thread again!

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....a body start!!!.. I think I have an idea of what is a body start but!!!!!!!! I do not want to make a fool out of me!!!. Please just tell me what is a body start!. You do not mean external power like CSU......you mean something else!!..no no no I have to read the thread again!

Tusker,

The word is "buddy" start. If you have an engine with an inop. starter, after removing the starter you taxi your acft. to a position close behind a buddy acft. This acft. then throttles up. The prop wash will then cause the subject engine on your acft. to rotate and upon achieving ignition/fuel flow and with continuing prop wash the engine will reach ground idle. We used this procedure a lot in RVN. Especially in places you didn't want to be hung up overnite. The down side was when you got the acft. home and did an eng. intake inspect. you often discovered FOD, especially if the buddy start was accomplished on unprepared surface. If memory serves, seem to remember the prop of the engine to be started would be placed in flt. idle. Am sure the old FEs can provide details. Of course the above procedure can be used if the GTC is inop.

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